[Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces.

David S. Miller
2003-05-16T00:06:03Z

From: Colin Ngam <cngam@sgi.com>
Date: Thu, 15 May 2003 18:45:42 -0500

Something else I do not understand .. in the PCI world, what does
Physical Memory Address got to do with 32Bit Mapped DMA
Bus Address?

Many platforms direct map, that is what I assumed was happening
here and causing the problems.

I have not seen any of the drivers broken yet - e.g. qlXXX, acenic,
tg3 etc.

It only works because these devices happen to allow >32-bit DMA
addresses for descriptors. You will find eventually that many
comodity pieces of PCI-X hardware will opt to only support 32-bit
DMA addressing for descriptor tables and whatnot.